There are two limiting factors which reduce the applicability of cardiac MRI (CMRI). The first one is that CMRI examination requires too much scanner time to be performed and many dummy planning scans before the relevant information is acquired. The second one is the high training degree required from technicians to be able to perform cardiac examinations with the right cardiac orientations, making difficult to be spread in any environment. Volumetric 3D isotropic acquisition covering the whole chest could help to avoid these two limitations and improving the cardiac examination workflow.
The scientific paper »L. H. Hamilton et al.: “Time-Resolved parallel Imaging with reduced Dynamic Field of View”; Magn. Reson. Med. 2011; 65:1062-74.<<describes a method named “Parallel Imaging and Noquist in Tandem” (PINOT) for accelerated dynamic image acquisation for cardial MRI (CMRI). This method combines the SPACE-RIP implementation of parallel imaging with the Noquist reduced field of view (rFOV) imaging method, which both use a direct inversion model for image reconstruction.
In PINOT reconstruction it is required to solve a linear system equation like
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In case of 3D cardiac MR images the size of this system matrix becomes difficult to manage and the system inversion to produce image reconstruction is extremely CPU-intensive.
US2014/0303480 describes a method of processing signals from an accelerated MRI scan of a dynamic event occurring in the body of a human patient. The patient is subjected to an MRI examination which includes the relevant portion of his body. Those voxels for which there is no substantially no change over time of the scan are identified and subtracted from the overall scan signal.